Engine driven apparatus such as an automobile, generally use a mechanical transmission to control torque for driving the wheels. To move the apparatus from idling or travelling in an inclined orientation, a larger torque is required than when the apparatus is already travelling in a relatively level surface or travelling in a declining orientation. A transmission is used to change the torque so that the engine can continue to run smoothly.
The transmission is either an automatic type or a manual type. Both the manual type transmission and the automatic type transmission are complex in design. They have gears with different number of teeth. Transmissions for semi trailers have about 12 to 15 gears. The manual type transmission requires a mechanical clutch to disengage the transmission from the engine when shifting gears or idling. The automatic type transmission does not have a clutch, instead it uses a fluid coupling, clutches usually two, bands usually, oil pumps, servos, control valve assembly, governor, and other components connected between the engine and the transmission. About two gallons of oil is also required.
The above transmissions have discrete gear changes which are noticeable when changing gears. Toyota Prius, a hybrid car, uses a complicated planetary gear set to control a variable pitch pulley arrangement which acts as a continuously variable transmission (CVT). The gear set and the pulley arrangement are bulky and the car body is specially designed to accommodate components around them. Accordingly, the gear set and the pulley arrangement cannot be retrofitted into other vehicles.
The prior art transmissions require regular maintenance to ensure that the gears or the gear/pulley set up are properly positioned, in good order and that there is sufficient oil. Loss of oil pressure would invariably damage the transmission components. Therefore, the casings of these transmissions must have a sealing arrangement that would prevent oil leak at high operating temperatures.